freebsd-skq/sys/fs/nullfs/null_vfsops.c

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/*-
* Copyright (c) 1992, 1993, 1995
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* The Regents of the University of California. All rights reserved.
*
* This code is derived from software donated to Berkeley by
* Jan-Simon Pendry.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94
*
* @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
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* $FreeBSD$
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*/
/*
* Null Layer
* (See null_vnops.c for a description of what this does.)
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
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#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <fs/nullfs/null.h>
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static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
static vfs_fhtovp_t nullfs_fhtovp;
static vfs_mount_t nullfs_mount;
static vfs_quotactl_t nullfs_quotactl;
static vfs_root_t nullfs_root;
static vfs_sync_t nullfs_sync;
static vfs_statfs_t nullfs_statfs;
static vfs_unmount_t nullfs_unmount;
static vfs_vget_t nullfs_vget;
static vfs_extattrctl_t nullfs_extattrctl;
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/*
* Mount null layer
*/
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static int
nullfs_mount(struct mount *mp)
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{
int error = 0;
struct vnode *lowerrootvp, *vp;
struct vnode *nullm_rootvp;
struct null_mount *xmp;
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char *target;
int isvnunlocked = 0, len;
struct nameidata nd, *ndp = &nd;
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NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
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if (mp->mnt_flag & MNT_ROOTFS)
return (EOPNOTSUPP);
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/*
* Update is a no-op
*/
if (mp->mnt_flag & MNT_UPDATE) {
/*
* Only support update mounts for NFS export.
*/
if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
return (0);
else
return (EOPNOTSUPP);
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}
/*
* Get argument
*/
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error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
if (error || target[len - 1] != '\0')
return (EINVAL);
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/*
* Unlock lower node to avoid deadlock.
* (XXX) VOP_ISLOCKED is needed?
*/
if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
VOP_ISLOCKED(mp->mnt_vnodecovered)) {
VOP_UNLOCK(mp->mnt_vnodecovered, 0);
isvnunlocked = 1;
}
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/*
* Find lower node
*/
NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread);
error = namei(ndp);
/*
* Re-lock vnode.
*/
if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered))
vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
if (error)
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return (error);
NDFREE(ndp, NDF_ONLY_PNBUF);
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/*
* Sanity check on lower vnode
*/
lowerrootvp = ndp->ni_vp;
/*
* Check multi null mount to avoid `lock against myself' panic.
*/
if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
NULLFSDEBUG("nullfs_mount: multi null mount?\n");
vput(lowerrootvp);
return (EDEADLK);
}
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xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
M_NULLFSMNT, M_WAITOK); /* XXX */
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/*
* Save reference to underlying FS
*/
xmp->nullm_vfs = lowerrootvp->v_mount;
/*
* Save reference. Each mount also holds
* a reference on the root vnode.
*/
error = null_nodeget(mp, lowerrootvp, &vp);
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/*
* Make sure the node alias worked
*/
if (error) {
VOP_UNLOCK(vp, 0);
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vrele(lowerrootvp);
free(xmp, M_NULLFSMNT); /* XXX */
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return (error);
}
/*
* Keep a held reference to the root vnode.
* It is vrele'd in nullfs_unmount.
*/
nullm_rootvp = vp;
nullm_rootvp->v_vflag |= VV_ROOT;
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xmp->nullm_rootvp = nullm_rootvp;
/*
* Unlock the node (either the lower or the alias)
*/
VOP_UNLOCK(vp, 0);
if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
MNT_ILOCK(mp);
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mp->mnt_flag |= MNT_LOCAL;
MNT_IUNLOCK(mp);
}
MNT_ILOCK(mp);
mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE;
MNT_IUNLOCK(mp);
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mp->mnt_data = xmp;
vfs_getnewfsid(mp);
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vfs_mountedfrom(mp, target);
NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
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mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
return (0);
}
/*
* Free reference to null layer
*/
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static int
nullfs_unmount(mp, mntflags)
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struct mount *mp;
int mntflags;
{
void *mntdata;
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int error;
int flags = 0;
NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
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if (mntflags & MNT_FORCE)
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flags |= FORCECLOSE;
/* There is 1 extra root vnode reference (nullm_rootvp). */
error = vflush(mp, 1, flags, curthread);
if (error)
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return (error);
/*
* Finally, throw away the null_mount structure
*/
mntdata = mp->mnt_data;
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mp->mnt_data = 0;
free(mntdata, M_NULLFSMNT);
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return 0;
}
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static int
nullfs_root(mp, flags, vpp)
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struct mount *mp;
int flags;
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struct vnode **vpp;
{
struct vnode *vp;
NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
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(void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
(void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
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/*
* Return locked reference to root.
*/
vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
VREF(vp);
#ifdef NULLFS_DEBUG
if (VOP_ISLOCKED(vp))
panic("root vnode is locked.\n");
#endif
vn_lock(vp, flags | LK_RETRY);
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*vpp = vp;
return 0;
}
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static int
nullfs_quotactl(mp, cmd, uid, arg)
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struct mount *mp;
int cmd;
uid_t uid;
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void *arg;
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{
return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg);
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}
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static int
nullfs_statfs(mp, sbp)
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struct mount *mp;
struct statfs *sbp;
{
int error;
struct statfs mstat;
NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
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(void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
(void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
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bzero(&mstat, sizeof(mstat));
error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat);
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if (error)
return (error);
/* now copy across the "interesting" information and fake the rest */
sbp->f_type = mstat.f_type;
sbp->f_flags = mstat.f_flags;
sbp->f_bsize = mstat.f_bsize;
sbp->f_iosize = mstat.f_iosize;
sbp->f_blocks = mstat.f_blocks;
sbp->f_bfree = mstat.f_bfree;
sbp->f_bavail = mstat.f_bavail;
sbp->f_files = mstat.f_files;
sbp->f_ffree = mstat.f_ffree;
return (0);
}
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static int
nullfs_sync(mp, waitfor)
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struct mount *mp;
int waitfor;
{
/*
* XXX - Assumes no data cached at null layer.
*/
return (0);
}
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static int
nullfs_vget(mp, ino, flags, vpp)
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struct mount *mp;
ino_t ino;
int flags;
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struct vnode **vpp;
{
int error;
error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
if (error)
return (error);
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return (null_nodeget(mp, *vpp, vpp));
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}
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static int
nullfs_fhtovp(mp, fidp, vpp)
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struct mount *mp;
struct fid *fidp;
struct vnode **vpp;
{
int error;
error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp);
if (error)
return (error);
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return (null_nodeget(mp, *vpp, vpp));
}
static int
nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname)
struct mount *mp;
int cmd;
o Change the API and ABI of the Extended Attribute kernel interfaces to introduce a new argument, "namespace", rather than relying on a first- character namespace indicator. This is in line with more recent thinking on EA interfaces on various mailing lists, including the posix1e, Linux acl-devel, and trustedbsd-discuss forums. Two namespaces are defined by default, EXTATTR_NAMESPACE_SYSTEM and EXTATTR_NAMESPACE_USER, where the primary distinction lies in the access control model: user EAs are accessible based on the normal MAC and DAC file/directory protections, and system attributes are limited to kernel-originated or appropriately privileged userland requests. o These API changes occur at several levels: the namespace argument is introduced in the extattr_{get,set}_file() system call interfaces, at the vnode operation level in the vop_{get,set}extattr() interfaces, and in the UFS extended attribute implementation. Changes are also introduced in the VFS extattrctl() interface (system call, VFS, and UFS implementation), where the arguments are modified to include a namespace field, as well as modified to advoid direct access to userspace variables from below the VFS layer (in the style of recent changes to mount by adrian@FreeBSD.org). This required some cleanup and bug fixing regarding VFS locks and the VFS interface, as a vnode pointer may now be optionally submitted to the VFS_EXTATTRCTL() call. Updated documentation for the VFS interface will be committed shortly. o In the near future, the auto-starting feature will be updated to search two sub-directories to the ".attribute" directory in appropriate file systems: "user" and "system" to locate attributes intended for those namespaces, as the single filename is no longer sufficient to indicate what namespace the attribute is intended for. Until this is committed, all attributes auto-started by UFS will be placed in the EXTATTR_NAMESPACE_SYSTEM namespace. o The default POSIX.1e attribute names for ACLs and Capabilities have been updated to no longer include the '$' in their filename. As such, if you're using these features, you'll need to rename the attribute backing files to the same names without '$' symbols in front. o Note that these changes will require changes in userland, which will be committed shortly. These include modifications to the extended attribute utilities, as well as to libutil for new namespace string conversion routines. Once the matching userland changes are committed, a buildworld is recommended to update all the necessary include files and verify that the kernel and userland environments are in sync. Note: If you do not use extended attributes (most people won't), upgrading is not imperative although since the system call API has changed, the new userland extended attribute code will no longer compile with old include files. o Couple of minor cleanups while I'm there: make more code compilation conditional on FFS_EXTATTR, which should recover a bit of space on kernels running without EA's, as well as update copyright dates. Obtained from: TrustedBSD Project
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struct vnode *filename_vp;
int namespace;
const char *attrname;
{
o Change the API and ABI of the Extended Attribute kernel interfaces to introduce a new argument, "namespace", rather than relying on a first- character namespace indicator. This is in line with more recent thinking on EA interfaces on various mailing lists, including the posix1e, Linux acl-devel, and trustedbsd-discuss forums. Two namespaces are defined by default, EXTATTR_NAMESPACE_SYSTEM and EXTATTR_NAMESPACE_USER, where the primary distinction lies in the access control model: user EAs are accessible based on the normal MAC and DAC file/directory protections, and system attributes are limited to kernel-originated or appropriately privileged userland requests. o These API changes occur at several levels: the namespace argument is introduced in the extattr_{get,set}_file() system call interfaces, at the vnode operation level in the vop_{get,set}extattr() interfaces, and in the UFS extended attribute implementation. Changes are also introduced in the VFS extattrctl() interface (system call, VFS, and UFS implementation), where the arguments are modified to include a namespace field, as well as modified to advoid direct access to userspace variables from below the VFS layer (in the style of recent changes to mount by adrian@FreeBSD.org). This required some cleanup and bug fixing regarding VFS locks and the VFS interface, as a vnode pointer may now be optionally submitted to the VFS_EXTATTRCTL() call. Updated documentation for the VFS interface will be committed shortly. o In the near future, the auto-starting feature will be updated to search two sub-directories to the ".attribute" directory in appropriate file systems: "user" and "system" to locate attributes intended for those namespaces, as the single filename is no longer sufficient to indicate what namespace the attribute is intended for. Until this is committed, all attributes auto-started by UFS will be placed in the EXTATTR_NAMESPACE_SYSTEM namespace. o The default POSIX.1e attribute names for ACLs and Capabilities have been updated to no longer include the '$' in their filename. As such, if you're using these features, you'll need to rename the attribute backing files to the same names without '$' symbols in front. o Note that these changes will require changes in userland, which will be committed shortly. These include modifications to the extended attribute utilities, as well as to libutil for new namespace string conversion routines. Once the matching userland changes are committed, a buildworld is recommended to update all the necessary include files and verify that the kernel and userland environments are in sync. Note: If you do not use extended attributes (most people won't), upgrading is not imperative although since the system call API has changed, the new userland extended attribute code will no longer compile with old include files. o Couple of minor cleanups while I'm there: make more code compilation conditional on FFS_EXTATTR, which should recover a bit of space on kernels running without EA's, as well as update copyright dates. Obtained from: TrustedBSD Project
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return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp,
namespace, attrname);
}
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static struct vfsops null_vfsops = {
.vfs_extattrctl = nullfs_extattrctl,
.vfs_fhtovp = nullfs_fhtovp,
.vfs_init = nullfs_init,
.vfs_mount = nullfs_mount,
.vfs_quotactl = nullfs_quotactl,
.vfs_root = nullfs_root,
.vfs_statfs = nullfs_statfs,
.vfs_sync = nullfs_sync,
.vfs_uninit = nullfs_uninit,
.vfs_unmount = nullfs_unmount,
.vfs_vget = nullfs_vget,
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};
VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);